The head-mounted display device directs the video image light emitted from the miniature image displayer (e.g., a transmissive or reflective liquid crystal displayer, an organic electroluminescent element, or a DMD element) to the pupil of the user by optical technology to implement virtual magnified images in the near-eye range of the user, so as to provide the user with intuitive, visual images, video, text information, which can be applied to outdoor, simulated driving, training, presentation, teaching, training, medical treatment, flight and other scenes.
The eyepiece optical system is the core of the head-mounted display device, which realizes the function of displaying a miniature image in front of human eyes to form a virtual magnified image. The design of the eyepiece optical system directly affects the key factors such as the volume, the visual experience and so on of the head-mounted display device, especially for the optical system applied in an optical non-perspective head-mounted display device, which requires to achieve a large field-of-view in a small size, a high optical resolution for seeing enough picture details, while obtaining long-term viewing without causing visual fatigue. However, in the related art of the conventional head-mounted display device which has been disclosed so far, no optical system suitable for use in an optical non-perspective head-mounted display device has been found.
U.S. Pat. No. 7,180,675B2 has disclosed an optical system of a viewfinder which is composed of two groups of positive and negative optical elements and refraction and reflection apparatuses. However, this optical system just obtains a display effect with a field-of-view of about 18°, and a serious chromatism greater than 0.5 mm between C-line and F-line. Accordingly, such optical system cannot achieve a higher resolution of the optical display, so cannot be applied to the optical non-perspective head-mounted display device.
U.S. Pat. No. 8,531,774B2 has disclosed an optical system of a viewfinder which is composed of two positive lenses, one negative lens and a reflection unit. As both positive and negative optical lenses are placed between the eyes of the observer and the reflection unit, this optical system can obtain a field-of-view of about 26°, however, it has short exit pupil position (<11 mm), and large size along the viewing direction. When such optical system is applied to the optical non-perspective head-mounted display device, the requirements of comfortable wearing cannot be satisfied. Meanwhile, the optical image aberration is large and it is too difficult to obtain an image quality realizing a high-resolution optical effect. Accordingly, such optical system is not benefit for long-term comfort visual experience.